Synthetic colours

Some studies have shown that eating foods containing synthetic colours may affect behaviour in children and teenagers. Others suggest these colours may pose a health risk. Learn more about synthetic colours, why they're used, and how they may affect health.

Why are synthetic colours used?

Food manufacturers add colours to food to improve its attractiveness. Synthetic colours are used instead of natural colours because they are:

more stable across a wider range of conditions

less expensive to use.

Reactions to synthetic colours

Synthetic food colours, particularly tartrazine, have occasionally been linked to adverse reactions like asthma and allergy-like reactions like rashes and headaches. These cases are rare and usually occur only in people who have other allergies.

Synthetic food colours have also been linked to hyperactivity in children and teenagers.

No clear link between synthetic colours and hyperactivity

Some behavioural studies have suggested that products containing synthetic colours may increase hyperactive tendencies in children who are sensitive to these ingredients.

However, this link is not clear, because it's difficult to work out how much of this behaviour is due to food colouring alone.

Other factors also affect study results, including:

the methods used to define and observe hyperactive behaviour

differences between children

what other stimuli are in the environment.

In 2007, the University of Southampton released results of a study looking at the impact of synthetic food colourings and additives on children's behaviour. While a small effect was seen, not all children reacted in the same way, or consistently, to these colours.

Animal studies show most colours have no health effect

Many animal toxicology studies have tested the effects of synthetic food colours. For most colours, animals had no adverse effects – even when given high doses (the colour making up 5% of the animals' diets). These are much higher levels than a person typically eats (about 0.01% of their diet).

The exceptions were high dose effects related to amaranth (calcium deposits in the kidneys) and erythrosine (impaired thyroid function). Acceptable daily intakes – internationally agreed limits for food additives – for these colours have been set to be well below dose levels where effects were observed and also include large safety factors.

NZ children and teenagers eating safe levels

Studies of dietary intake of colours suggest it's unlikely that New Zealand children are eating synthetic food colours at levels likely to pose a health risk.

Dietary intakes were estimated based on research from 2 studies:

the 1999/2000 food colours survey – which looked at mean levels of food colours in confectionery and beverages

the 2002 National Children's Nutrition Survey (2002 CNS), which looked at dietary intakes for more than 3,000 children and teenagers.

Dietary estimates were adjusted for differences in body weight, and compared to the internationally agreed acceptable daily intakes (ADIs). Average intakes for all food colours considered were less than 5% of the relevant ADI.

Even children and teenagers eating high amounts of food colours – in the top 5% of those surveyed – ate at most 15% of the relevant ADIs.

Use of synthetic colours regulated

All food additives, including synthetic colours, must be assessed for safety by Food Standards Australia New Zealand (FSANZ).

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